Piston Ring Set 4.390 Bore 1/16 1/16 3/16

The JE PISTONS Piston Ring Set 4.390 Bore 1/16 1/16 3/16 (SKU JEPJ10008-4390-5) is a premium race-series ring kit engineered for high-performance eight-cylinder engines requiring file-fit installation. This four-piece set combines low-tension design with ductile iron construction and plasma moly coating to deliver superior ring sealing, reduced friction, and extended durability in demanding engine applications where precision and reliability are non-negotiable.

The 4.390-inch bore diameter positions this ring set for mid-range to large-displacement eight-cylinder engines common in race and performance builds. The 1/16-inch top two ring thicknesses provide optimal gas sealing and blowby control, while the 3/16-inch oil ring thickness manages crankcase ventilation and lubrication film consistency. Low-tension engineering reduces parasitic drag on the crankshaft, improving power output and fuel efficiency—critical factors in both road-course and drag-racing environments. Plasma moly plating on the bearing surfaces enhances wear resistance and extends ring life under continuous high-RPM operation.

File-fit rings demand precision cylinder wall preparation and careful installation clearance verification. This specification appeals to engine builders and machine shops performing full ring and cylinder refreshes who control bore dimensions and can accommodate the hand-fitting process. The kit is designed for eight-cylinder engines where bore uniformity and top-deck flatness have been verified to OEM or racing specifications. Proper installation requires matching the ring set to exact bore measurements and verifying end-gap clearance before final assembly.

JE PISTONS manufactures this ring set to race-series standards, making it suitable for high-revving naturally aspirated and forced-induction eight-cylinder platforms found in competition vehicles and performance street builds. Buyers should confirm their engine's exact bore size and ring groove dimensions match the 4.390-inch specification before ordering, and consult engine builders or machine shops regarding installation requirements for file-fit ring sets.